A lay-flat pipe is a pipe which, when unpressurised, is substantially flat and, when pressurized by a relatively low pressure, has a substantially circular cross section, similar to a fire hose. Such pipes are usually made of a flexible material and are mainly employed in irrigation systems, where they may be used as manifold pipes.
In the field of irrigation, such pipes are normally formed with plug holes disposed along the pipe, the pipe area surrounding each plug hole being used for mounting thereon pipe inserts for connection thereto of additional irrigation means such as branch pipes or the like, as disclosed for example in GB 2,187,622. Alternatively, inserts may be used to plug holes that are not in use, such as disclosed for example in U.S. Pat. No. 5,560,654. In both cases, the inserts have to be sealingly mounted into the plug holes to prevent leakage of liquid from the pipe, the pipe area surrounding each plug hole thus constituting the pipe's sealing area.
Inserts of the above kind normally comprise an internal unit and a fastener, each having a sealing portion and a mounting portion, such as disclosed in GB 2,187,622 mentioned above. The sealing portion of the internal unit is formed with a flange adapted to be forced into a plug hole. The mounting portion of the fastener is adapted to be snapped or screwed onto the mounting portion of the internal unit, so as to clamp the sealing area of the pipe surrounding the plug hole between the sealing portions of the internal unit and the fastener. The flange is usually formed with a raised edge adapted to facilitate sealing contact with the pipe's sealing area.